<p>The dust has barely settled from the furor around Gmail's tabbed inbox when another change comes down the pike. I noticed late last week that Gmail has started caching images, though there hadn't been an announcement from Google. I wasn't the only one who noticed, either.</p><p>There is no doubt there will be cries that Google has, once again, killed email marketing. But to understand what impact this may have requires that we start by understanding what has changed.</p><p>Email messages are, by and large, pretty static. Once they're sent, they're fixed. The one exception is the images, which are downloaded when the recipient reads the message. As that happens, a treasure trove of information is shared with the image host. Many enterprising companies including ESPs, MovableInk, ReturnPath, Litmus and AudiencePoint use that data in a variety of ways.</p><p>By switching to caching the images, Google has caused that source of information to largely dry up.</p><p><a href="http://www.clickz.com/clickz/column/2317772/google-quietly-updates-gmail-to-cache-images-impact-for-email-marketers">Keep reading...</a></p>